The stages of fishes that are discussed in this conference are those that are collected by hauling plankton nets in the oceans. These are the eggs, larvae and less frequently the juveniles of marine fishes. There are three principal reasons why ichthyoplankton surveys are made. Firstly, the surveys are often directed toward a single target species in order to use the distribution and abundance of the pelagic eggs to obtain an estimate of the biomass of the adult spawning population. Secondly, the larvae of a target species are studied in order to estimate the success of the year brood resulting from its spawn and hopefully to understand the factors underlying fluctuations in survival. The third reason is to use ichthyoplankton surveys to evaluate fish resources in general. At last, there are many larval characters that can aid significantly in differentiating taxa and in defining evolutionary lineages within a family or order.